The United States has outlined plans for new economic sanctions against Russia for enabling the government of Bashar Assad in the ongoing crisis in Syria.

Stepping up the pressure on the Syrian president, US Ambassador to the United Nations Nikki Haley indicated the sanctions to be announced on Monday would be aimed at sending a message to Russia, which she said has blocked six attempts by the UN Security Council to make it easier to investigate the use of chemical weapons.

RT @USUN: “If Russia had lived up to its commitment, there would be no chemical weapons in Syria, and we would not be here today.” pic.twitter.com/re7XiE2jnJ

Ms Haley also made it clear that the United States will not be pulling troops out of Syria right away, saying US involvement there “is not done”.

Ms Haley said the three US goals for accomplishing its mission are making sure chemical weapons are not used in a way that could harm US national interests; that the Islamic State group is defeated; and that there is a good vantage point to watch what Iran is doing.

“We’re not going to leave until we know we’ve accomplished those things,” she said.

Ms Haley said the joint military strike “put a heavy blow into their chemical weapons programme, setting them back years” and reiterated that if Assad uses poison gas again, “the United States is locked and loaded”.

Russia has military forces, including air defences, in several areas of Syria to support Assad in his long war against anti-government rebels.

Russia and Iran called the use of force by the United States and its French and British allies a “military crime” and “act of aggression”.

The UN Security Council met to debate the strikes, but rejected a Russian resolution calling for condemnation of the “aggression” by the three Western allies.

Assad denies he has used chemical weapons, and the Trump administration has yet to present hard evidence of what it says precipitated the allied missiles attack: a chlorine gas attack on civilians in Douma on April 7.

The US says it suspects that sarin gas also was used.

“Good souls will not be humiliated,” Assad tweeted, while hundreds of Syrians gathered in Damascus, the capital, where they flashed victory signs and waved flags in scenes of defiance after the early morning barrage.